The overall goal of this research is to study the mechanism of light energy transduction in visual pigments and related pigments using resonance Raman spectroscopy. This technique is a very powerful one to probe the structure and changes in structure of the visual pigment retinal chromophore that accompany the early stages of vision. The ultimate goal is to understand from a molecular viewpoint how light energy is converted to that chemistry that is called visual transduction. Transduction processes are important problems in biology, and a molecular understanding of the visual system is an important step. Three main areas of study are envisioned. Experiments are planned to elucidate the nature of the chromophoric site. The structure of the primary photoproducts are to be measured so as to understand how light energy is converted to chemical energy. Lastly, dark intermediates and reaction pathways are to be probed to help elucidate how this chemical energy is used.